code: def add_length(x: str) -> int:
      return len(x)
  
imports: from __future__ import annotations
  import sys
  from unittest import mock
  from absl.testing import absltest
  from google.generativeai.notebook import post_process_utils
  from google.generativeai.notebook import post_process_utils_test_helper
  from google.generativeai.notebook.lib import llm_function
  from google.generativeai.notebook.lib import llmfn_output_row
  from google.generativeai.notebook.lib import model
label_desc: Use image node_id 1 for calling a global function with example usage: add_length(x) and returns: len